Answer: Sounds suspiciously like rust on your roses, a common foliar diseases. Begin to control by cleaning up any debris under your plants, and keeping fallen leaves and blooms picked up all year. Prune your roses and remove all the prunings from the garden. You'll not only cut out any diseased plant parts, but you'll also open the plants up to better air circulation, which will help your plants avoid diseases later in the season. Make sure your roses are in full sunshine (8-10 hours each day) and keep water off the leaves, or make sure the leaves have ample time to dry before nightfall. To avoid the spread of disease development, monitor your plants and pinch or prune off any leaves that develop spots.
There is a new product available called Soap Shield Fungicidal Soap that is described as an environmentally-friendly copper-based fungicide effective against black spot and rust on roses. It might be worth a try.
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